… the development of secondary sexual characteristics can be costly… The costs include potential suppression of immune functions, increased risk of predation (e.g., for brightly colored males), and increased aggression from conspecifics, among others….

… delayed maturation allows males to grow larger and gain the social and behavioral competencies needed to compete for and attract mates…

Le bambine maturano prima…

… girls grow up faster than boys: that is, they reach 50% of their adult height at an earlier age …, enter puberty earlier and cease earlier to grow …. At birth the difference corresponds to 4 to 6 weeks of maturation and at the beginning of puberty to 2 years. (Tanner, 1990, p. 56)…

… The slower maturation of boys (see Garai & Scheinfeld, 1968; Hutt, 1972) appears to heighten their risk of early mortality but contributes to their adult height; later puberty results in longer legs in men than in women, relative to overall height…

… Boys also develop larger hearts as well as larger skeletal muscles, larger lungs, higher systolic blood pressure, lower resting heart-rate, a greater capacity for carrying oxygen in the blood, and a greater power of neutralizing the chemical products of muscular exercise …. In short, the male becomes more adapted at puberty for the tasks of hunting, fighting and manipulating all sorts of heavy objects. (Tanner, 1990, p. 74)…

… hormonal increase… also influence the expression of a wide range of social, behavioral, and sexual differences (Hayward, 2003). As examples, the hormonal changes influence the emergence of sexual fantasy… For boys, there is a marked increase in sexual behavior, especially masturbation…

… During childhood there are small to moderate differences favoring boys in tasks such as grip strength, jumping distance, and running speeds, with large differences emerging during adolescence (Thomas & French, 1985); by 17 years of age, more than 9 out of 10 boys outperform the average girl in these areas…

… As a result of the sex difference in leg length, muscle mass, and cardiovascular capacity, men can run faster, on average, than women (Deaner, 2006). By far, the largest differences in physical competencies are for throwing distance and throwing velocity (Thomas & French, 1985)…

Lo scheletro maschile diventa più adatto al lancio di oggetti…

… The sex differences in throwing skills are related to differences in the structure of the supporting skeletal system. Relative to overall body height, boys have a longer ulna and radius (i.e., forearm), on average, than do girls (Gindhart, 1973)….

… Of course, some physical sex differences, such as the wider pelvic region in women, have evolved through natural rather than sexual selection. Once the large pelvis evolved, the waist-to-hip ratio that men find attractive emerged and began to be shaped by male choice…

… Girls are also more physically flexible than boys and have an advantage in fine eye–motor coordination…

La manipolazione “sottile” sembra migliore nelle donne…

… Kimura (1987) argued that the advantage of girls and women might be related to manipulating objects “within personal space, or within arm’s reach, such as food and clothing preparation and child care” (p. 145)…

… Related to the need to grow larger and stronger than girls is slower growth, beginning prenatally: Boys are born “premature” relative to girls. They have higher activity levels and higher basal metabolic rates than girls, resulting in higher caloric requirements for normal development…

… boys will be more sensitive—suffer more physical, social, and cognitive deficits—than girls when growing up in poor conditions, including poor nutrition, inadequate health care, or poor social stimulation…

… An analysis of 16,000 infant deaths in the United States between 1983 and 1987, inclusive, revealed that boys had a 38% higher mortality rate due largely to infectious disease during the 1st year of life (J. S. Read, Troendle, & Klebanoff, 1997)…

… Poor early physical development, exposure to parasites, frequent illness, poor nutrition, and inadequate social and cognitive stimulation have been shown to be related to poor long-term cognitive, academic, and social outcomes, even after controlling for SES and other confounds (S. P. Walker, Chang, Powell, & Grantham-McGregor, 2005). Sex differences are not typically reported in these studies, but boys’ risk of poor early growth and development is likely to result in an overrepresentation of boys and men with poor long-term outcomes…

… Breast-fed infants of both sexes had normal IQ scores at age 8 years… For the two groups that were not breast fed, the risk of cerebral palsy or other significant cognitive impairments was 5 to 6 times higher for boys who received standard formula compared with boys who received the supplement. The risk was not elevated for girls. In fact, the mean IQ of girls was in the average range and did not vary across conditions…

… The flip side of boys’ greater vulnerability may be an enhanced potential to benefit more than girls from an enriched environment. This hypothesis has not been tested, although there were hints of such an effect in the Lucas et al. (1998) study…

… M. Alexander (2003) hypothesized that some of the early sex differences in orientation toward people (more in girls) or things (more in boys) reflect the evolved skeletal structure of the visual system, specifically, biases in the what and where visual pathways. Prenatal and early postnatal exposure to androgens may enhance development of the latter and result in attentional and perceptual biases for processing spatial location and object motion…

… Orientation toward other people is measured in terms of the duration of eye contact, empathy for others’ distress, and time spent looking at faces, among other behaviors…

La cosa è già riscontrata nel primo giorno di vita…

… “there is no doubt that girls and women establish and maintain eye contact more than boys and men. The earliest age for which this is reported is one day”… The sex difference in time spent looking at the face was small but consistent with studies of older infants (McClure, 2000)…

Le ragazzine hanno più memoria per i volti…

… By this age, girls might also have a better memory for faces and might be more skilled in discriminating two similar faces (e.g., J. F. Fagan, 1972)…

… Infant girls may react with greater empathy than infant boys to the distress of other people (M. L. Hoffman, 1977). Simner (1971) found that infant girls cried longer than infant boys when exposed to the cry of another infant, but there was no sex difference in reflexive crying when the infants were exposed to artificial noise of the same intensity…

Nel rapporto con i genitori le bambine hanno una marcia in più…

… Studies of the quality of social interactions between parents and infants also reveal that girls are more responsive, and perhaps more sensitive, to social cues than boys (Freedman, 1974; Gunnar & Donahue, 1980; W. D. Rosen, Adamson, & Bakeman, 1992)… In a related study with 6- to 12-month-olds, Gunnar and Donahue (1980) found that mothers were just as likely to attempt to initiate social interactions with their sons as with their daughters, but daughters were much more responsive; Whiting and Edwards (1988) reported the same pattern with older children across cultures…

Il contatto visivo madre-figlia non ha paragoni…

… K. A. Buss, Brooker, and Leuty (2008) found that 2-year-old girls sought contact with and stayed closer to their mother than did boys in a fear-eliciting situation… In an intensive naturalistic study of mother–infant interactions from birth to 3 months, Lavelli and Fogel (2002) found that girls spent more time in face-to-face communication with their mothers than did boys….

… In an intensive naturalistic study of mother–infant interactions from birth to 3 months, Lavelli and Fogel (2002) found that girls spent more time in face-to-face communication with their mothers than did boys….

Riassumendo…

… Males appear to be more likely to store information about the various components of a repeatedly presented stimulus, for example, its form and color …. [while] females, unlike males, are more likely to store information about the consequences of orienting. (p. 382)…

… Baron-Cohen and his colleagues have been studying how prenatal exposure to testosterone influences sex differences in infancy and in older children (Baron-Cohen, Lutchmaya, & Knickmeyer, 2004; Lutchmaya, Baron-Cohen, & Raggatt, 2002a, 2002b)… Testosterone gets into the amniotic fluid by diffusion through the fetus’s skin and through urination…

Testosterone e contatto visivo…

… Lutchmaya et al. (2002a) examined the relation between prenatal testosterone levels and the frequency with which 12-month-olds made eye contact with their mother… Prenatal testosterone levels were, however, related to how often the boys made eye contact but not in a straightforward way…

Testosterone e linguaggio…

… Lutchmaya et al. (2002b) assessed the vocabulary of boys and girls at 18 and 24 months. At 18 months, the vocabulary of girls was more than double that of boys. At 24 months, the typical girl knew 40% more words than did the typical boy. At this age, higher prenatal testosterone levels were associated with lower vocabulary scores…

***

Bambini e bambine giocano diversamente, è un dato universale…

… sex differences in play activities are a universal aspect of children’s behavior…

A sei mesi il sessismo dei bambini è già notevole…

… Infants begin to make sex-based discriminations (e.g., between male and female voices) as early as 6 months of age (C. L. Martin, Ruble, & Szkrybalo, 2002). By 18 months, they are beginning to categorize some activities as male typical and others as female typical (Eichstedt, Serbin, Poulin-DuBois, & Sen, 2002), and they talk about these as 2-year-olds (S. A. Gelman, Taylor, & Nguyen, 2004)…

… Girls and boys segregate into same-sex groups whether or not they are engaging in sex-typed activities (Maccoby, 1988), and children raised by egalitarian parents—those who actively discourage sex typing—have less stereotyped beliefs about sex differences than do children raised in other types of families, but their toy and play preferences are the same as these other children (Weisner & Wilson-Mitchell, 1990)…

… Rough-and-tumble play is more common among boys and play parenting is more common among girls… The sex difference in rough-and-tumble play emerges by age 3 years… This sex difference is found in all modern societies…

… The sex difference is most evident with groups of three or more children and in the absence of adult supervision…

I ragazzini nutrono un maggior interesse per il gruppo…

… The sex difference in infants’ interest in groups (Benenson et al., 2004) continues into childhood and beyond. These studies confirm that boys organize themselves into much larger social groups than do girls, engage in intergroup competition once such groups are formed, form within-group dominance hierarchies, and show within-group role differentiation and specialization when engaged in group-level competition (Eder & Hallinan, 1978; Lever, 1978)… More often, boys compete as members of teams and must simultaneously coordinate their actions with those of their teammates while taking into account the action and strategies of their opponents…

… In an observational study, Hines and Kaufman (1994) found that girls affected by CAH engaged in more playful physical assaults, physical assaults on objects, wrestling, and rough-and-tumble play in general than did unaffected girls, but none of these differences were statistically significant…

… Throughout the world, girls are assigned child-care roles, especially for infants, more frequently than are boys (Whiting & Edwards, 1988). Girls also seek out and engage in child care, play parenting, and other domestic activities (e.g., playing house) with younger children or child substitutes such as dolls more frequently than do same-age boys (Pitcher & Schultz, 1983)…

E’ comune anche alle culture antiche e agli altri primati…

… In sum, a sex difference in play parenting favoring girls is found in both modern and traditional societies and in fact most other species of primate (Eibl-Eibesfeldt, 1989; Nicolson, 1987)…

E per quanto riguarda i giochi esplorativi e itineranti?

In quasi tutte le società l’uomo si muove e viaggia di più…

… Across traditional societies, men travel farther from the home village than do women for many reasons, including finding mates, developing alliances with the men of neighboring villages, hunting, and intergroup warfare (Chagnon, 1997; K. Hill & Hurtado, 1996; K. Hill & Kaplan, 1988)… Women’s foraging, in contrast, typically occurs within the group’s territory… Unlike women’s foraging for fruit or tubers, hunting requires an ability to track and predict the movements of evasive prey, human and nonhuman…

… The sex difference is related in part to the sex difference in group-level competitive play and to a greater engagement of boys than girls in solitary running (Eaton & Enns, 1986; Lever, 1978)… During juvenility and beyond, boys have a larger play range than girls…

… Whenever it emerges, boys not only engage in more locomotor activities over a larger range than girls but also explore and manipulate (e.g., build things, such as forts) the ecology much more frequently (Matthews, 1992)…

… ecological exploration is correlated with the ability to generate mental maps of the physical layout of the ecology but is not consistently related to other forms of spatial cognition, such as the ability to copy geometric figures (R. H. Munroe et al., 1985)…

… Levine et al. assessed 547 children from high-, middle-, and low-income backgrounds across second and third grades on two spatial tasks—map reading and two-dimensional mental rotation—and a syntax comprehension test. No sex differences were found on the syntax test, but boys from high- and middle-income families had an advantage on both spatial tasks. There was no sex difference on either spatial task for children from low-income families. In other words, low family income was associated with lower scores for both boys and girls on all three tests…

… An analysis of the relation between the focus of play activities and the pattern of cognitive abilities indicated that children whose play was object oriented “performed better on tests of ability to organize and classify physical materials” (Jennings, 1975, p. 515), as assessed by tests of spatial cognition (e.g., the ability to mentally represent and manipulate geometric designs) and the ability to sort objects on the basis of, for example, color and shape…

Anche le differenze vocazionali sono interessate…

… As I review elsewhere (Geary, 1998b), there are sex differences in interest in and pursuit of careers that involve designing and working with mechanical objects, as in engineering and computer technology…

Altre evidenze del discrimine…

… Chen and Siegler (2000) found that as early as 18 months of age, boys have small to moderate advantages over girls in several aspects of early tool use, as in using a hooked stick to retrieve a desired toy. Boys were better at applying tool-related knowledge learned in one setting to another setting, were more consistent in the use of tools across settings, and were more successful in the use of tools in problem solving. Without any hints from an adult, 79% of the boys and 31% of the girls were able to use such tools to retrieve the toy…

… Both boys and girls regularly engage in sociodramatic play but differ in the associated themes and the roles they tend to adopt, as noted by Pitcher and Schultz (1983): Boys play more varied and global roles that are more characterized by fantasy and power. Boys’ sex roles tend to be functional, defined by action plans. Characters are usually stereotyped and flat with habitual attitudes and personality features (cowboy, foreman, Batman, Superman). Girls prefer family roles, especially the more traditional roles of daughter and mother. Even at the youngest age, girls are quite knowledgeable about the details and subtleties in these roles …. From a very early age girls conceive of the family as a system of relationships and a complex of reciprocal actions and attitudes. (p. 79)…

… In a longitudinal study of children in the United States, Maccoby and Jacklin (1987) found that 4- to 5-year-olds spent 3 hours playing with same-sex peers for every single hour they spent playing in mixed-sex groups. By the time these children were 6 to 7 years old, the ratio of time spent in same-sex versus mixed-sex groups was 11:1…

… In situations in which access to a desired object, such as a movie viewer that can be watched by only one child at a time, is limited, boys and girls use different strategies, on average, for gaining access to this object (Charlesworth & Dzur, 1987). More often than not, boys gain access by playfully shoving and pushing other boys out of the way, whereas girls gain access by means of verbal persuasion (e.g., polite suggestions to share) and sometimes verbal commands (e.g., “It’s my turn now!”)…

Un maschietto è sordo allo stile femminile.

Gli ormoni sono correlati allo stile dei giochi…

… The sex difference in play interests is related to prenatal exposure to male hormones… social correlates of amniotic testosterone levels…

La segregazione spontanea rafforza le differenze…

… The net result of sex segregation is that boys and girls spend much of their childhood in distinct peer cultures (J. R. Harris, 1995; Maccoby, 1988). It is in the context of these cultures that differences in the social styles and preferences of girls and boys become larger and congeal (C. L. Martin & Fabes, 2001)…

… children’s attentional, behavioral, and social systems are inherently biased such that they will recreate the forms of relationship (e.g., as in mother–infant attachment) and experience that help them navigate the developmental process and that prepare them for the survival and reproductive demands of our adult ancestors (Caporael, 1997)…

… The coalitions are of course fluid because the gains of victory are distributed—often unequally according to dominance rank—among coalition members. The result is a balance between the benefits of having a large enough ingroup coalition to be competitive against the costs of having to share gains with ingroup members…

… In comparison with girls and women, boys and men are predicted to have a lower threshold for forming cooperative same-sex social relationships; their relationships are predicted to be more easily maintained (e.g., with less time-intensive disclosure) and evince a greater tolerance for interpersonal conflict. The results from studies of peer relationships support all of these predicted sex differences (Benenson & Christakos, 2003; Benenson et al., 2009; Eder & Hallinan, 1978; Rose & Rudolph, 2006; Whitesell & Harter, 1996). Tolerance for conflict is necessary to maintain the coalition and at the same time compete for within-coalition status. Dominance striving must, at the same time, be balanced against the cost of potentially losing the coalitional support of other boys and men…

… The principle benefit for girls and women is a core set of relationships that provide social, emotional, and interpersonal stability, particularly support during times of interpersonal conflict with other individuals, such as a spouse…

… Within these same-sex groups, both boys and girls formed dominance hierarchies and frequently used ridicule to establish social dominance, such as name calling (“homo,” “perverted groin”) or gossiping; social…

… In some groups, boys began their bid for dominance within hours of arriving in the cabin, whereas most of the girls were superficially polite for the first week and then began to exhibit dominance-related behaviors…

Vediamo più da vicino i metodi maschili…

… Boys’ dominance-related behaviors included ridicule, as noted previously, as well as directives (“Get my dessert for me.”), counterdominance statements (“Eat me.”), and physical assertion (e.g., play wrestling, pillow fights, sometimes actual physical fights). More than 90% of the time these behaviors were visible to all group members, were clearly directed at one other boy, and were attempts to establish dominance over this individual…

E quelli femminili…

… Girls used ridicule, recognition, and verbal directives to establish social dominance but used physical assertion only one third as frequently as did boys. In contrast to boys’ blatant behaviors, more than one half of the girls’ dominance behaviors were indirect…

… As documented in other studies (J. G. Parker & Seal, 1996), Savin-Williams (1987) found that by the end of summer camp boys’ groups showed greater stability and cohesiveness relative to the 1st week of camp. Most of the girls’ groups, in contrast, were on the verge of splintering or had already split into “status cliques based on popularity, beauty, athletics, and sociability” (Savin-Williams, 1987, p. 124)…

Andy, il maschio dominante nel campeggio…

… Andy [the alpha male] immediately grabbed the flag cloth and penciled a design; he turned to Gar for advice, but none was given. Otto [low ranking] shouted several moments later, “I didn’t say you could do it!” Ignoring this interference, Andy wrote the tribal name at the top of the flag. Meanwhile, Delvin and Otto were throwing sticks at each other with Gar watching and giggling. SW [the counselor] suggested that all should participate by drawing a design proposal on paper and the winning one, as determined by group vote, would be drawn on the flag…. Andy, who had not participated in the “contest,” now drew a bicentennial sunset; it was readily accepted by the others. Without consultation, Andy drew his design as Gar and Delvin watched. Gar suggested an alteration but Andy told him “Stupid idea,” and continued drawing. Otto, who had been playing in the fireplace, came over and screamed, “I didn’t tell ya to draw that you Bastard Andy!” Andy’s reply was almost predictable, “Tough shit, boy!” (Savin-Williams, 1987, p. 79)…

Ann, la femmina dominante del campeggio…

… [Her] style of authority [was] subtle and manipulative, she became the cabin’s “mother.” She instructed the others on cleanup jobs, corrected Opal’s table manners (“Dottie, pass Opal a napkin so she can wipe the jelly off her face.”), and woke up the group in the morning …. Ann became powerful in the cabin by first blocking Becky’s [the beta female] dominance initiations through refusing and shunning and then through ignoring her during the next three weeks. By the fifth week of camp Ann effectively controlled Becky by physical assertion, ridicule, and directive behaviors. (Savin-Williams, 1987, p. 92)…

Tratti in comune…

… For both boys and girls, the achievement of social dominance was related to athletic ability, physical maturity, and leadership…

In generale le relazioni tra ragazze si addolciscono nel tempo…

… Ahlgren and Johnson found that at about the time of puberty, girls’ social motives become more cooperative and less competitive than those of their younger peers…

… Boys’ relationships changed as well. By late adolescence, boys’ group-level games were characterized by greater focus and organization, with fewer negative criticisms and more encouragement directed toward ingroup peers than was found with younger boys (Savin-Williams, 1987)…

… In comparison with boys’ friendships, girls’ friendships are characterized by higher levels of emotional support and more frequent intimate exchanges (e.g., talking about their problems) and are a more central source of help and guidance in solving social and other problems (Maccoby, 1990; J…

Le ragazze sono meno brusche e più disposte al compromesso…

… Conflicts of interest are common among friends of both sexes, but girls invest more in resolving these conflicts and attempt to do so through accommodation, compromise…

… girls are more sensitive to personal slights on the part of their best friend and respond with more initial and lingering negative affect (e.g., sadness, anger) than do boys (Whitesell & Harter, 1996)…

… boys’ and men’s concerns about social dominance and their relative hierarchical position and girls’ and women’s social agreeableness and tendency to nurture is found across modern and traditional societies (e.g., Del Giudice, 2009a; Feingold, 1994; Whiting & Edwards, 1988)…

… The reduction in the sex difference in physical size since the australopithecines and the corresponding reduction in the variability across hominid brain volumes make it very likely that the average brain size of our male and female ancestors has converged since the emergence of Homo…

… Pakkenberg and Gundersen (1997) found that in comparison with women’s brains, men’s brains, on average, are 13% heavier, occupy 15% more volume, and contain 16% more neurons, among other differences… M. Leonard et al. (2008) found that the overall brain size of more than 9 out of 10 men was larger than that of the average woman… The 10% male advantage in brain size is found in newborns and continues into childhood, juvenility, and adolescence…

… Overall, men have more gray matter (neuronal cell bodies and dendrites that collect information from other cells) and white matter (neuronal axons that transmit information to other cells) than women…

… One of the more controversial findings concerns the corpus callosum, the bundle of axons that allows communication across the left and right hemispheres. De Lacoste-Utamsing and Holloway (1982) reported that the back portion of the callosum was shaped differently in men and women and that relative to overall brain weight was larger in women. They speculated “that the female brain is less well lateralized—that is, manifests less hemispheric specialization…

… More men than women are left-handed, and language and spatial functions tend to be more strongly localized in the left and right hemispheres, respectively, in men and distributed across both hemispheres in women (McGlone, 1980; Witelson, 1976, 1991). Kelso, Nicholls, Warne, and Zacharin (2000) found more left-handers and better nonverbal than verbal abilities for girls and women with CAH…

… An intriguing example is provided by a brain imaging study of amygdala activation, which is involved in the processing of emotionally and sexually laden information, when individuals with CAH viewed facial expressions that conveyed neutral and negative affect (i.e., fear or anger; Ernst et al., 2007);…

***

Quando una donna pensa a sé pensa al suo ruolo in famiglia…

… When reflecting on or describing themselves (e.g., completing “I am …”), women are more likely than men to view themselves in terms of close relationships with family members or friends, whereas men are more likely to view themselves as members of groups or teams (Gabriel & Gardner, 1999)…

… girls and women appear to be more aware of nuances in their feelings and emotions than boys and men and have better memories for the details of emotionally charged personal experiences (Barrett, Lane, Sechrest, & Schwartz, 2000)… My interpretation is that girls and women are better able to use awareness of their feelings as a social barometer…

Le donne appaiono più ossessionate dal loro corpo…

… In general, girls and women tend to reflect on their behavior and traits more frequently than do boys and men across many domains (Fejfar & Hoyle, 2000), and their bodies are a common area of reflection…

… amygdala is among the core brain systems involved in the processing of emotion-laden information and is structurally and functionally different in women and men (e.g., Goldstein et al., 2001; Kilpatrick et al., 2006)…

Lo stesso dicasi per la corteccia pre-frontale…

… After correcting for the sex difference in brain size and size of the frontal cortex, the social–emotional processing areas of the prefrontal cortex are larger in women than in men…

Lo stesso dicasi per i due emisferi cerebrali (più connessioni in quello sinistro per le donne e in quello destro per gli uomini)…

… In addition to the sex differences in proportional size of the amygdala (larger in men) and ventromedial prefrontal cortex (larger in women), these regions are interconnected differently in women and men (Kirkpatrick et al., 2006; Tranel, Damasio, Denburg, & Bechara, 2005). There appears to be greater functional connectivity between these regions in the right hemisphere for men and the left hemisphere for women…

… prenatal exposure to male testosterone may bias the later functioning of the amygdala (Ernst et al., 2007), and men’s larger amygdala may be due to the pubertal increase in testosterone (Neufang et al., 2009)…

Sul linguaggio, la differenza non riguarda tanto la loquacità…

… Girls talk more than boys during the first 2 years of life and during the juvenile period (about 10–13 years), but boys may talk more during adolescence (Leaper & Smith, 2004). At…

… Pragmatics refers to the use of language in social contexts. Boys and men tend to use language to attempt to assert their social dominance…

I vantaggi linguistici della donna sono comunque innumerevoli…

… Relative to boys and men, girls and women have advantages for many basic language-related skills, including the length and quality of utterances (e.g., in their utterances women show standard grammatical structure and a correct pronunciation of language sounds more frequently than do men), the ease and speed of articulating complex words, the ability to generate strings of words, the speed of retrieving individual words from long-term memory, and skill at discriminating basic language sounds from one another (R. A. Block, Arnott, Quigley, & Lynch, 1989; D. F. Halpern, 2000; Hampson, 1990a; Hyde & Linn, 1988; Majeres, 2007)…

… women are predicted to invest more in their children than are men, as is the case for mammals in general (Clutton-Brock, 1991). Ample support for this prediction was provided in chapter 6 of this volume…

I maschi però restano curiosamente interessati ai parenti maschi…

… A less obvious prediction is that men will show a bias for male kin, especially when their group is engaged in frequent intergroup conflict…

… I assume gay men are discriminated against by other men because of an implicit assumption that gay men’s contributions to male–male coalitional competition will be limited; whether this is the case remains to be determined…

… social identification enables the formation of larger and therefore more competitive social groups, and one of the core selection pressures for the establishment and maintenance of large competitive groups is coalitional male–male competition… If this hypothesis is correct, then social identification with competitive groups (e.g., a sports team, a nationality) should be more easily instantiated in men than in women…

… women showed more agreement among themselves about the classification of these species, showed greater complexity in their overall classification system, and had more nuanced knowledge about individual species…

… In a study of the Paniya and Kuruma tribes in India, Cruz García (2006) found that mothers were more knowledgeable of local plants than fathers and passed this folk biological knowledge to their children; children also learn from other adults and from peers (Setalaphruk & Price, 2007)…

… In support of the predicted developmental sex difference, there is some indication that boys attend to potentially dangerous and wild animals more often than do girls and know more about these animals (Blurton Jones, Hawkes, & O’Connell, 1997; Eibl-Eibesfeldt, 1989; Setalaphruk & Price, 2007)…

… For normal adults, McKenna and Parry (1994) found that women were better at naming fruits and vegetables and men were better at naming animals, but other studies have not found this sex difference (Barbarotto et al., 2002); men are better at naming tools, however (see the section titled Tool Use later in this chapter)…

… I suspect the differences arise from the combination of sex differences inherent in attentional and interest biases and corresponding sex differences in engagement with the biological world. The tendency of boys to attend to wild and potentially dangerous animals more frequently than girls might reflect such an attentional bias, and their play hunting, a corresponding activity that would eventually result in a sex difference favoring men, might result in knowledge of local fauna (Blurton Jones et al., 1997; Eibl-Eibesfeldt, 1989)…

… I return to G. M. Alexander’s (2003) hypothesis about the development of the where as contrasted with the what stream of the visual system (see the section titled Infancy, chap. 10, this volume), specifically, that prenatal and early postnatal exposure to testosterone may enhance aspects of the development and functioning of the where system and result in a sex difference favoring boys in interest in object motion…

… About 8% of men have varying degrees of color blindness, that is, they are poor at discriminating colors in the red–green spectrum; about 2% of men cannot discriminate red from green at all (Nathans, Piantanida, Eddy, Shows, & Hogness, 1986). Discrimination of red from green appears to be an evolved feature of the primate visual system that supports the detection of fruit and other colorful foods (Shyue et al., 1995), and thus these men should be at an evolutionary disadvantage…

Gli uomini sono più abili nell’identificare velocità e traiettoria…

… Men also show advantages in the ability to judge the velocity and trajectory of a moving object, generate visual images of a moving object, estimate when an object moving directly toward them will hit them, and hit a moving object with a thrown projectile (Pavio & Clark, 1991; Schiff & Oldak, 1990)…

… As I mentioned in chapter 10 of this volume (in the section titled Physical Competencies), boys and men have a very large advantage over same-age girls and women in throwing distance, velocity, and accuracy (Thomas & French, 1985)…

… When asked to generate a map after exploring a novel environment, boys’ maps showed more accurate clustering of environmental features and more accurate representations of the geometric relations—cardinal direction (e.g., Building A is northwest of Building B)—among these features (Matthews, 1992)…

… Boys and girls also differed in the extent to which they focused on landmarks (e.g., specific buildings) or routes (e.g., roadways) in their maps. In this study and others, girls have been found to attend more to landmarks and relative direction (Building A is left of Building B) and boys to routes and cardinal direction (see also J. Choi & Silverman, 2003)…

… tool construction is much more common among men than women across traditional societies (Daly & Wilson, 1983; Murdock, 1981); boys have a better intuitive sense of how to use objects as tools and learn how to use tools more quickly than do girls (Z. Chen & Siegler, 2000; Gredlein & Bjorklund, 2005)…